A heat sink is the main path for dissipating heat from a CPU. CPUs develop considerable amounts of heat, with more powerful CPUs creating even more heat. With CPUs producing ever-increasing amounts of heat, and proper CPU function depending in part on dissipating that heat, a heat sink is an important addition to a circuit board.
Although typical heat sinks may be capable of dissipating heat, an improved heat sink may benefit a system by reducing the required air flow and, consequently, reducing the power consumed by the fan.
There are several traditional ways to improve heat sink performance. For example, a heat sink may use material of higher conductivities, such as copper (Cu) as the fin material. A heat sink may use heat pipes and heat spreader to distribute heat within the fins. Also, if space allows, the demand for better convective heat transfer may be met by more and taller heat sink fins.
However, traditional ways to improve heat sink performance have their drawbacks. Cu is heavier and more expensive—it becomes impractical to use Cu in heat sinks for servers with 1.5 U and 2 U form factors. Adding heat pipes to transport heat within heat sinks requires cutting holes in the heat sink fins, which is a complicated process and also reduces the convective area. A heat spreader may improve the heat distribution, but that does not otherwise improve fin efficiency. And for taller heat sinks (e.g., 1.5 U or 2 U, where a 1.5 U heat sink height may be 45 mm or less and a 2 U heat sink may be from 45 to 75 mm), the thermal resistance between heat source and fin end is increased, which may reduce the efficiency of such heat sinks.
Furthermore, heat sink design may be limited by the available package volume. For example, a heat sink design may be limited to the volume available in a server with a 2 U form factor, which is typically 90 mm×90 mm×64 mm (LWT). Another pre-determined volume may be 90 mm×116 mm×64 mm.
Therefore, the need exists for a more efficient heat sink. Also, the need exists for a more efficient heat sink that will fit in a pre-defined volume.